Chapter 2 – The Chemistry of Life: Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering the key chemical, structural, and functional concepts presented in Chapter 2: The Chemistry of Life.

Biochemistry

The study of the molecules (carbohydrates, lipids, proteins, nucleic acids) that compose living organisms.

Element

The simplest form of matter with unique chemical properties; identified by its atomic number.

What is a simple definition of trace elements?

Trace elements are chemical elements that are present in very small amounts in a substance, typically making up less than 0.01\% of its composition, but are essential for its proper function or health.

Atomic Number

The number of protons in the nucleus of an atom.

Mineral

Inorganic element extracted from soil by plants; important for body structure and enzyme function.

Isotope

Variety of an element differing only in neutron number; chemically similar to other isotopes of the same element.

Radioisotope

Unstable isotope that decays, emitting ionizing radiation.

Physical Half-Life

Time required for 50 % of a radioisotope to decay to a stable state.

Biological Half-Life

Time required for 50 % of a radioisotope to disappear from the body.

Ion

Charged particle with unequal numbers of protons and electrons.

Radioisotope

Unstable isotopes that decay, emitting radiation

Anion

Negatively charged ion produced by gaining electrons.

Cation

Positively charged ion produced by losing electrons.

Electrolyte

Substance that ionizes in water and forms an electrically conductive solution.

Free Radical

Short-lived particle with odd number of electrons; highly reactive and damaging.

Antioxidant

Chemical that neutralizes free radicals (e.g., vitamin E, SOD).

Molecule

Two or more atoms united by chemical bonds.

Compound

Molecule composed of two or more different elements.

Molecular Formula

Notation showing element symbols and the number of each atom in a molecule (e.g., C6H12O6).

Structural Formula

Diagram showing the arrangement of atoms in a molecule.

Isomer

Molecules with identical molecular formulas but different arrangements of atoms.

Chemical Bond

Force that holds atoms together or attracts molecules to each other.

Ionic Bond

Attraction between a cation and an anion; easily broken by water.

Covalent Bond

Chemical bond where atoms share one or more pairs of electrons.

Nonpolar Covalent Bond

Covalent bond with equal electron sharing.

Polar Covalent Bond

Covalent bond with unequal electron sharing, producing partial charges.

Hydrogen Bond

Weak attraction between a slightly positive hydrogen and a slightly negative oxygen or nitrogen atom.

Van der Waals Force

Weak, brief attraction due to fluctuating electron clouds; important in protein folding.

Mixture

Substances physically blended without chemical bonding (e.g., body fluids).

Solvency

Ability of a solvent (water) to dissolve other chemicals.

Hydrophilic

Water-loving; substances that dissolve in water because they are charged or polar.

Hydrophobic

Water-fearing; non-polar substances that do not dissolve in water.

Hydration Sphere

Cluster of water molecules surrounding and isolating ions in solution.

Adhesion

Attraction of water molecules to other substances.

Cohesion

Attraction of water molecules to each other, producing surface tension.

Heat Capacity

Amount of heat needed to raise 1 g of a substance 1 °C; high in water.

Solution

Homogeneous mixture with solute particles under 1 nm that remain evenly distributed.

Colloid

Mixture with particles 1–100 nm that scatter light but stay mixed (e.g., blood plasma proteins).

Suspension

Mixture with particles over 100 nm that settle on standing (e.g., blood cells).

Emulsion

Suspension of one liquid in another (e.g., oil in vinegar).

Acid

Proton donor that releases H⁺ in water.

Base

Proton acceptor that accepts H⁺ or releases OH⁻.

pH

Negative logarithm of hydrogen ion molarity; measures acidity/alkalinity.

Buffer

Chemical solution that resists pH changes.

Energy

Capacity to do work or cause change.

Potential Energy

Stored energy (e.g., chemical energy in bonds).

Kinetic Energy

Energy of motion, including heat and electromagnetic radiation.

Decomposition Reaction

Reaction where a large molecule breaks into smaller ones (AB → A + B).

Synthesis Reaction

Reaction where smaller molecules combine to form a larger one (A + B → AB).

Exchange Reaction

Reaction where two molecules exchange atoms or groups (AB + CD → AC + BD).

Reversible Reaction

Chemical reaction that can proceed in either direction depending on conditions.

Law of Mass Action

Direction of a reversible reaction is determined by the relative concentrations of reactants and products.

Catalyst

Substance that speeds up a reaction without being consumed; enzymes are biological catalysts.

Metabolism

Sum of all chemical reactions in the body.

Catabolism

Energy-releasing decomposition reactions.

Anabolism

Energy-storing synthesis reactions.

Oxidation

Loss of electrons; often releases energy.

Reduction

Gain of electrons; often stores energy.

Redox Reaction

Coupled oxidation-reduction process where electrons transfer between molecules.

Organic Chemistry

Study of carbon-containing compounds.

Carbon Backbone

Long chains or rings of carbon atoms forming the framework of organic molecules.

Functional Group

Small cluster of atoms that imparts specific chemical properties (e.g., hydroxyl, amino).

Monomer

Small subunit that can join to form a polymer.

Polymer

Large molecule made of repeating monomer units.

Dehydration Synthesis

Polymer-forming reaction that removes water as monomers join.

Hydrolysis

Reaction that splits polymers by adding water.

Carbohydrate

Hydrophilic organic molecule with general formula (CH2O)n; includes sugars and starches.

Monosaccharide

Simple sugar monomer such as glucose, fructose, or galactose.

Disaccharide

Sugar composed of two monosaccharides (e.g., sucrose, lactose, maltose).

Polysaccharide

Long chain of monosaccharides (e.g., glycogen, starch, cellulose).

Glycogen

Animal storage polysaccharide stored in liver, muscle, etc.

Starch

Plant storage polysaccharide digestible by humans.

Cellulose

Plant structural polysaccharide; dietary fiber indigestible to humans.

Lipid

Hydrophobic organic molecule with high H:O ratio; includes fats and oils.

Fatty Acid

Long hydrocarbon chain with carboxyl group; may be saturated or unsaturated.

Triglyceride

Neutral fat composed of glycerol plus three fatty acids; primary energy storage lipid.

Phospholipid

Amphipathic lipid with two fatty acids and a phosphate group; forms cell membranes.

Eicosanoid

20-carbon lipid derived from arachidonic acid; hormone-like signaling molecule (e.g., prostaglandins).

Steroid

Lipid with four fused carbon rings; includes cholesterol and hormones.

Cholesterol

Parent steroid; component of cell membranes and precursor to other steroids.

HDL (High-Density Lipoprotein)

Blood lipoprotein with low lipid-to-protein ratio; ‘good’ cholesterol carrier.

LDL (Low-Density Lipoprotein)

Blood lipoprotein with high lipid-to-protein ratio; ‘bad’ cholesterol carrier.

Protein

Polymer of amino acids performing numerous biological functions.

Amino Acid

Building block of proteins; contains amino, carboxyl, and variable R group.

Peptide Bond

Covalent bond linking the carboxyl group of one amino acid to the amino group of another.

Conformation

Unique three-dimensional shape of a protein necessary for its function.

Denaturation

Irreversible loss of protein conformation due to extreme heat or pH.

Primary Structure

Linear sequence of amino acids in a protein.

Secondary Structure

Coiled or folded shape (alpha helix or beta sheet) stabilized by hydrogen bonds.

Tertiary Structure

Further folding due to interactions among R groups; produces globular or fibrous shape.

Quaternary Structure

Association of two or more polypeptide chains in a protein.

Enzyme

Protein catalyst that lowers activation energy and speeds biochemical reactions.

Active Site

Region on an enzyme where the substrate binds.

Cofactor

Non-protein helper (ion or molecule) required for enzyme activity.

Coenzyme

Organic cofactor derived from vitamins (e.g., NAD⁺).

Metabolic Pathway

Chain of enzymatically catalyzed reactions converting a substrate to an end product.

Feedback Inhibition

End product of a pathway inhibits an early enzyme, regulating the pathway.

ATP (Adenosine Triphosphate)

Primary energy-transfer nucleotide with three phosphate groups.

Phosphorylation

Addition of a phosphate group to a molecule, often activating it.

ADP (Adenosine Diphosphate)

ATP after losing one phosphate; can be re-phosphorylated to ATP.